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PATENT Errea..

ADDISON O. FLETCHER, OF NEW YORK, N. Y.

GRATE-BAR.

Specification forming part of Letters Patent No. 53,966, dated April 17, 1866.

To all whom t may concern:

Be it known thatI, ADDISON C. FLETCHER, of the city, county, and State of New York, have invented a new and useful Improvement in Grate-Bars; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a side view of a grate-bar constructed according to my invention. Fig. 2is alongitudinal vertical section of the same. Fig. 3 is a plan ofthe same, partly in section. Fig. 4 is a horizontal section of the longitudinal braces by which the bar is strengthened. Fig. 5 is a diagram, illustrating the application of my improved grate-barsv to a boiler-furnace.

Similar letters of reference indicate correspondin g parts in the several gures.

This invention consists in the construction of grate-bars with their faces in the form of a series of steps, one above another, and with a series of air-passages so arranged in the rising portions of said steps that air which is heated in its passage through them is delivered over the surface of the fuel on the steps below in such manner as to inflame the combustible gases eliminated from the fuel.

It also consists in the bracing of the steps of the bar by means of longitudinal vertical braces, as hereinafter described.

To enable others skilled in the art to make and use my invention, I will proceed to describe it with reference to the drawings.

The series of steps A' A, the upper surfaces of which form the face of the grate-bar, are represented in Figs. 1 and 2. These steps are connected together by transversely-arranged vertical webs a a. On the sides of the bar there are lateral projections b b, as in other grate-bars,for the purpose of keeping the steps of the adjacent bars at the proper distance apart, making the horizontal profiles of the bars of substantially the same form as those of ordinary grate-bars, as shown in Fig. 3. In the steps there are parallel openings, c c, of any suitable form, through which, as well. as through the spaces between the bars, air is admitted to the fuel on the steps. In the edges of the webs a a there are notches g g, so arranged that when the said webs of two bars meet each other in the grate the said notches in the two bars will be opposite each other, and so combine to form an air-passage like dd. In the upper parts of the vertical webs a a are airpassages d d, of circular or other form-either horizontal or inclined--for the admission of air from below the grate-bar above the fuel 011 the steps.

e c are the longitudinal vertical braces for the strengthening of the bar, extending longitudinally from the transverse web a of each step to the corresponding web of the next one above or below, and connected in the casting with the upper parts of their respective steps. These braces may be straight, but I prefer to make them corrugated vertically, as shown in Fig. 4, that they may the more readily expand in a longitudinal direction as the upper portions of the steps are expanded by heat. The bars thus constructed may be arranged to form the grate, either side by side and parallel, or radiating from a common center, and in the latter case they may be arranged either with their highest steps at the center, but preferably with theirlowest steps at the center, which would give the grate an amphitheatrical form.

The best arrangement for the furnace of a cylinder-boiler will be parallel and transverse to the boiler, using two bars for the width of the grate, with their lower ends abutting together under the center of the width of the boiler, as shown in Fig. 5, in which the line f represents the transverse sectional proiile of the lower part of the boiler. By this arrangement the whole width of the grate and the bed of fuel upon it is kept at nearly uniform distance from the boiler, so as to subject nearly the whole of the lower semi-diameter of the boiler to a nearly uniform heating influence, which is one great advantage derived from the construction of the grate in step form.

The gratebars thus constructed may be supported in the usual or any suitable manner, which will :readily suggest itself to the engineer, according to their arrangement. They may be applied to all kinds of furnaces, stoves, and fireplaces.

The coal or other fuel is spread upon the steps A A of the grate-bars up, or nearly up, to the passages d in the webs a a, so that while air is admitted from below through the fuel by means of the passages c c in the steps andthe spaces between the bars, air is also admitted above the fuel through the passages d cl, as in- 2. In a grate with its face in the form of a dicated by arrows in Fig. 2, and the air adseries of steps, passages d d, for the admisinitted through the latter passages is so heated I sion of air above the fuel on the steps, substanbefore arriving above the steps that its oxygen ltially as and for the purpose herein set forth. combines readily with the carbonio oxideelimi- 3. The longitudinal vertical braces e e, connated from the fuel, and so produces a very necting the transverse Webs a a and the steps perfect and intense combustion. of a step-formed grate-bar, substantially as What I claim as my invention, and desire to herein described. secure by Letters Patent7 is- ADDISON G. FLETCHER.

1. A grate-bar with its face in the form of Witnesses: a series of steps, one above another, substan- HENRY T. BROWN, tially as and for the purpose herein specified. A. LECLERC. 

